McLaren boss Martin Whitmarsh has admitted to being left frustrated by his team's failure to nail its early advantage this season mainly due to mistakes.

Despite taking three pole positions, Lewis Hamilton has yet to win a race, the Englishman demoted to the back of the Barcelona grid after being excluded from the (qualifying) results due to an error that saw him sent out with too little fuel.

Prior to that however, there had been a catalogue of errors including strategic wrong calls and botched pit stops which compromised the efforts of Hamilton and his teammate, Jenson Button, leading to open criticism from fans and the British media.

"We should have had more success then we've had," he admitted to reporters in the latest Vodafone McLaren Mercedes phone-in. "I think in life, we all have moments of frustration and I'm very frustrated.

"We've got a reasonable car and two great drivers," he continued. "Either could win drivers' championship and this team could win the constructors' title. We're in a strong position. We are confident the issues we have had so far have been dealt with and are in the past. I'm mindful that in the present, there are always new things that can come and bite you so we should not be complacent and say we've sorted everything.

"We've made a range of changes within the team in terms of processes and personnel to deal with some of the issues," he continued. "Everyone in this company is mindful that a small humour error on their part could draw some difficulty in any of the races that are left this season."

Referring to Hamilton, who some predict will leave the Woking outfit when his contract runs out later this year, Whitmarsh added: "He's been unlucky. The last race was disappointing for the team, but Lewis should come away from there with very strong feelings about what he achieved this year.

"He has a car that is capable of being on pole, he has shown the speed and capability to be on pole and he's striving to greater levels of maturity then perhaps we've seen before. He's eight points away from the championship lead and he must consider himself a very strong candidate to winning Monaco and this world championship."